Obtaining seed-borne virus free mahaleb (Prunus mahaleb) genotypes through ‎meristem tip culture and in vitro thermotherapy

Mahaleb (Prunus mahaleb) plant is one of the most important sources of cherry clonal and seed base rootstock production in Iran. Obtaining seed-borne viruse-free (Prune dwarf virus, Plum pox virus, Prunus necrotic ringspot virus) sources for selected mahaleb rootstocks (NB5176, NBVP1, NBVP2), For this purpose, the viral infection status of genotypes was initially studied in orchard using ELISA serological method. Then the meristem tips were cultured in vitro and 6 months later, transferred to MS medium containing 0.5mg/l BAP and 0.1 mg/l NAA, DKW contacting 0.5 mg/l BAP and WMP contacting 0.3 mg/l pectin. After the initial proliferation stage, the plantlets were heat-treated and then health status of the remained plantlets was studied using RT-PCR. Then the healthy plants were rooted and transferred to pots. Based on ELISA result, some genotypes were probably infected to PNRSV and PDV. The highest shoot tip establishment was recorded as 42.5% by NBPV1. No genotype was proliferated in MS and WPM, so only DKW was apropriate for proliferation. For plantlet rooting, 1/2DKW and modified QL containing 1.5 mg/l IBA were appropriate. NBVP2 was the best in all rooting media. Most of plantlets from three genotypes toleratedin-vitro thermotherapy condition and were free of PNRSV, PDV, PPV based on RT-PCR result. The healthy plants were transferred to pots and could be cultured in an isolated orchard to obtain healthy mahaleb seeds.